If you need to know which version of Ubuntu you’re running, open System Settings and select Details. Alternatively, from the command line, type lsb_release -a.

For versions of Ubuntu between 14.04 LTS (Trusty Tahr) and 15.10 (Wily Werewolf), as well as Ubuntu flavours that don’t include snap by default, snap can be installed from the Ubuntu Software Centre by searching for snapd.